It is known in connection with cleaning or light polishing of floor surfaces to use a pad in the form of a three-dimensional non-woven web. The pad is usually provided as a circular, disc-shaped body, which is to be disconnectably mounted on a circular carrier plate, which in use is caused to rotate in a plane parallel with the floor surface, such that the pad, when brought into contact with the floor surface, is slightly compressed by the pressure arising between the floor surface and the carrier plate. The carrier plate is usually driven by a motor and may be mounted on a carrier frame, which may be arranged to be pushed or pulled by a walking operator or which may be arranged as a ridable vehicle.
Such pads are generally formed from fibers of an organic material, e.g. polyamide and/or polyester, particularly polyethylene terephtalate. In some cases the fibers also include natural fibers, such as walnut fibers or coconut fibers.
The fibers of the pad are generally interconnected at their mutual points of contact by so-called melt bonding, whereby the fibers are subjected to heat that cause the outer part of the fibers to slightly melt and thereby to bond to each other.
Alternatively, or additionally, the fibers may be interconnected at their mutual points of contact by the pad being impregnated with a polymer resin, hereinafter referred to as a “primary binder”.
Production of this type of non-woven pads is well known from e.g. U.S. Pat. No. 3,537,121, U.S. Pat. No. 4,893,439, EP-A-0 397 374, GB-A-1 348 526 and EP-B-0 562 919, and thus does not need to be further elaborated on herein.
U.S. Pat. No. 3,537,121 discloses pads for polishing surfaces of aluminum, plastic, wax and similar surfaces. U.S. Pat. No. 3,537,121 also discloses production of such pads. In U.S. Pat. No. 3,537,121 a binder mixed with abrasive particles is applied to the pad by passing the pad between a pair of squeeze rolls, one of which is partially immersed in a container for a mixture of binder resin and abrasive particles, after which the pad is allowed to cure or dry. Thus, in U.S. Pat. No. 3,537,121 a pad is provided, which is entirely impregnated by the binder and abrasive particles.
U.S. Pat. No. 4,893,439 discloses a pad for polishing floor surfaces or aluminum. The pad consists of fibers of organic material and constitutes a lofty open non-woven structure, and contains a binder binding abrasive particles to the fibers. The pad shown in U.S. Pat. No. 4,893,493 has larger voids than that shown in U.S. Pat. No. 3,537,121, and thereby has an improved ability to absorb dirt, so that it can be used for a longer period. Also the pad disclosed in U.S. Pat. No. 4,893,493 is entirely impregnated by binder and abrasive particles.
EP-A-0 397 374 discloses a pad for floor polishing machines, which also is entirely impregnated by binder and abrasive particles.
Pads of the above type are frequently used for so-called “burnishing”, i.e. dry polishing (often on a daily basis) of very lightly worn surfaces at high speed (1500-3000 rpm) and relatively low pressure, with a view to restoring a polished surface. This type of treatment is commonly used for both vinyl and marble floorings. Pads suitable for this purpose are available from 3M™ under the designation “3M™ Floor Pads”, and provide no or little effect on very hard floor surfaces, such as terrazzo or concrete, which have been subject to wear for a longer period of time.
EP-B-0 562 919 discloses a non-woven pad of polymer fiber, which is entirely impregnated by a binder comprising a mixture of curable plastic resin and abrasive particles having a particle size of 0.1-30 μm. As examples of curable resins are mentioned phenol resin, acrylic resins, melamine resin and urea resin. Diamond is mentioned as one among several other examples of plausible abrasive particles. However, according to EP-B-0 562 919, the pad disclosed therein is suitable for treatment of marble floor surfaces, and only in combination with crystallization chemicals, which means that treatment must be made in the presence of liquid containing a salt-forming acid.
The pad in EP-B-0 562 919 is also provided by passing a non-woven pad through a nip between two squeeze rolls, one of which being partially immersed in a binder/abrasive particles mixture, such that the binder and abrasive particles, via the surface of the cylinder is distributed in the pad.
Since the pad disclosed in EP-B-0 562 919 is to be used in the presence of crystallization chemicals, the method described in EP-B-0 562 919 actually constitutes a vitrification method, used with a view to improving the stain resistance and durability of a marble floor. This method is not suitable for daily maintenance purposes, since it involves use of special crystallization chemicals, including acids, which are to react with calcium present in the floor surface to form insoluble calcium salts. Such a method is typically used once in connection with the initial preparation of the polished marble floor, and thereafter at intervals of 6-12 months. The method described in EP-B-0 562 919 is thus too complicated for being used on a daily basis.
Pads of the type referred to in EP-B-0 562 919 are sold by 3M® under the designations “3M™ 5200 Brown Stone Renew Pad” and “3M™ 4000 Grey Stone Polish Pad”, and are used for treating marble in the presence of crystallization chemicals and at relatively low speeds (below 250 rpm).
The need for crystallization chemicals makes the polishing work more complicated, since the chemicals are to be applied to the surface, possibly followed by removal of excess chemicals, which also contribute to making the polishing work more time consuming. Handling and application of the chemicals also constitute a potential hazard to the environment in general and to the work environment in particular.
It is also known to provide a polished stone or concrete surface by using tools comprising grinding or polishing elements made from a plastic resin mixed with abrasive particles, i.a. diamond particles. Since such elements are fixedly mounted on a usually rotating plate, they do not have the ability to compensate for unevenness in the floor, which may lead to uneven treatment of the floor surface, or to scratching or staining of the floor surface in case such an element is to contact the surface at an excess pressure. Yet another problem is that debris, such as grains of sand, small stones or metal may get stuck in or near the elements and cause scratching of the floor surface. Finally, this type of tools require special machinery capable of applying a higher pressure to the contact surface between the tool and the floor surface.
WO03/075734 discloses a disc-shaped device for cleaning purposes, comprising a nylon scouring material, which is arranged on a rigid disc, whereby grinding elements containing industrial diamonds are placed in recesses in the active scouring surface. A disadvantage with the device disclosed in WO03/07534 is that it does not eliminate the risk of debris getting stuck in or near the grinding elements. Yet another disadvantage is that this tool is complex and therefore more prone to breaking and more difficult and expensive to manufacture.
Hence, there is a need for an improved and simplified method and tool for daily maintenance of hard surfaces. Preferably, the method should be simple to use, e.g. by persons who do not have specialist training in floor surface preparation, and the method should be usable with conventional floor surfacing equipment, e.g. burnishing machines, etc. Also, the tools should be easy to manufacture, not too expensive, and it should be durable.